Yeah, somehow Apple completely removed the driver, so you're relying on the software driver (aka: no GPU) as if you were on a virtual machine. And without a working GPU, the GPU features in Photoshop are disabled.

I hope that's a temporary glitch in the beta. If not, we'll have to work it out with Apple.

I'm not sure. Let Apple know about the problem, though. They need to make sure it is correctly patched in their build or installer/updater (not sure where it went wrong).
Hopefully it's just a temporary glitch that will get fixed in the next build.